The Worldwide Fund for Nature had warned this week that the rapid melting of the glaciers — receding at among the fastest rates in the world because of global warming — would initially cause floods in India, China and Nepal but would lead to water shortage within a few decades.

However, WWF’s country experts fear that the worst may not be all that far away. “We are probably in the stage where flash floods are still occurring during monsoon with contribution from melting of the glaciers, as happened in upper Bihar last year when huge melting in Nepal coupled with significant rainfall, but the river flows might have been already affected during summer months,” one of them said.

A senior climate researcher of WWF–India told The Telegraph today that the melting might have already crossed the critical level and the threat of disaster was looming large, especially on northern India.

“Though we are still working on it, the findings so far suggest that reduction of glacier masses has already crossed the critical level and the flow in the rivers catered to by these glaciers is also reducing,” said Samrat Sengupta, senior policy officer of climate change and energy programme at WWF-India.

The government should give urgent attention to the phenomenon and prepare the river policy accordingly, he said. “The government should take a fresh look at all river-related projects, whether it is development of hydel power plants or river linking.”

WWF warned about the threat from receding glaciers in a study report released this week before a two-day energy and environment ministerial roundtable in London of the 20 greatest energy-consuming countries, including the G8 nations.

India, China, Australia and Brazil are among the non-G8 nations at the conference.

The report said the glaciers are receding 10 to 15 metres a year on average and predicted that this might lead to water shortage in India, China and Nepal as seven of the greatest rivers in the region are fed by these glaciers.

The report said the rapid melting of Himalayan glaciers would first increase the volume of water in rivers, causing widespread flooding, but subsequently water levels in rivers would fall.

WWF–India is carrying out the Indian leg of the global study on glaciation, mainly in collaboration with a specialised organisation called High Ice, with secondary data from the past two-and-a-half decades and primary data generated during the project.

The Sunderbans section of the project began about six months ago and the early data confirms gradual increase in inundation of the area, changes in the microclimate and its resident life, said the state director of WWF-India.